In-plane switching mode liquid crystal display device

ABSTRACT

An in-plane switching mode liquid crystal display device includes a first substrate; a gate line disposed in a first direction on the first substrate; a data line disposed in a second direction on the first substrate, the data line crossing the gate line to define a pixel region; pixel electrodes and common electrodes disposed in the first direction in the pixel region, the pixel electrodes and the common electrodes generating an in-plane electric field within the pixel region; first and second common lines disposed parallel to the data line at right and left sides of the pixel region; a first common electrode connection line connecting at least two common electrodes and forming a first common electrode overlapping region by overlapping the first common line; and a second common electrode connection line connecting at least two other common electrodes and forming a second common electrode overlapping region by overlapping the second common line, wherein the first common electrode overlapping region and the second common electrode overlapping region have substantially the same area.

This application claims the benefit of Korean Patent Application No.P2004-49777 filed in Korea on Jun. 29, 2004, which is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device andmore particularly, to an in-plane switching mode liquid crystal displaydevice and a method for fabricating the same.

2. Description of the Related Art

A liquid crystal display (LCD) device is commonly used as a flat paneldisplay device because it provides high quality images and consumes lowpower. The LCD device is formed by attaching face to face a thin filmtransistor array substrate and a color filter substrate with a uniformgap between the two substrates, and forming a liquid crystal layerbetween the two substrates. Pixels are arranged on the thin filmtransistor array substrate in a matrix. A thin film transistor, a pixelelectrode and a capacitor are formed in each pixel region. A commonelectrode, an RGB color filter, and a black matrix are formed on thecolor filter substrate. An electric field is generated between thecommon electrode and the pixel electrode and applied to the liquidcrystal layer. The RGB color filter implements colors.

Alignment films are formed at facing surfaces of the thin filmtransistor array substrate and the color filter substrate. The alignmentfilms are rubbed to arrange the liquid crystal layer in a specificdirection. Liquid crystals rotate due to a dielectric anisotropy whenthe electric field is applied to the liquid crystal layer between thepixel electrode formed in each pixel region and the common electrodeformed on the entire surface of the color filter substrate. The rotationof the liquid crystals causes individual pixel regions to transmit orblock light for displaying letters or images.

However, such a twisted nematic mode LCD device has a narrow viewingangle. Therefore, research is actively ongoing in developing an in-planeswitching (IPS) mode LCD device to solve the viewing angle problem. Inan IPS mode LCD device, liquid crystal molecules are aligned nearlyparallel to a substrate.

FIG. 1A is a plane view of a pixel region of the related art IPS-LCDdevice. FIG. 1B is a cross-sectional view taken along line I-I′ of FIG.1A. Referring to FIGS. 1A and 1B, a gate line 1 and a data line 3 arearranged horizontally and vertically on a transparent first substrate 10to define a pixel region. Although N gate lines 1 and M data lines 3cross each other to define N×M pixels in an actual LCD device, only onepixel is illustrated in the drawing to simplify the description.

A thin film transistor 9, including a gate electrode 1 a, asemiconductor layer 5 and source/drain electrodes 2 a and 2 b, isdisposed at the crossing of the gate line 1 and the data line 3, and thegate electrode 1 a and the source/drain electrodes 2 a and 2 b arerespectively electrically connected to the gate line 1 and the data line3. A common line 4 is arranged parallel to the gate line 1 within thepixel region, and at least one pair of electrodes switching liquidcrystal molecules, namely, a common electrode 6 and a pixel electrode 7are arranged parallel to the data line. The common electrode 6 is formedsimultaneously with the gate line 1 and electrically connected to thecommon line 4. A gate insulation layer 8 is formed over an entiresubstrate 10 including the common electrode 6. The pixel electrode 7 isformed on the insulation layer 8 simultaneously with the source/drainelectrodes 2 a/2 b and electrically connected to the drain electrode 2 bof the thin film transistor 9. A passivation film 11 is formed over theentire substrate including the source/drain electrodes 2 a and 2 b. Apixel electrode line 14 overlapping the common line 4 and electricallyconnected to the pixel electrode 7 forms a storage capacitance (Cst)with the insulation film 8 interposed between the common line 4 and thepixel electrode line 14.

A black matrix 21 for preventing light leakage to the thin filmtransistor 9, the gate line 1 and the data line 3, and a color filter 23are formed on a second substrate 20, and an overcoat film (not shown) isapplied on the coler filter 23 to flatten the color filter 23. Alignmentfilms 12 a and 12 b are applied to facing surfaces of the firstsubstrate 10 and the second substrate 20. The alignment films 12 a and12 b determine an initial alignment direction of the liquid crystals. Aliquid crystal layer 13 is formed between the first substrate 10 and thesecond substrate 20 in order to control transmittance of light by avoltage applied to the common electrode 6 and the pixel electrode 7.

The related art IPS-LCD device having the above-described structureimproves viewing angle because the common electrode 6 and the pixelelectrode 7 are placed on the same substrate and generate an in-planeelectric field. However, the IPS-LCD device has the following problems.Because the common electrode 6 and the pixel electrode 7, which isformed of an opaque metal, are placed within the pixel region where animage is displayed, and brightness degraded.

Furthermore, an in-plane electric field is not normally formed withinthe pixel region because of signal interference between the data line 3and the pixel electrode 7. The aperture is reduced when the width of thecommon electrode 6 adjacent to the data line 3 is increased to preventsignal interference between the data line 3 and the pixel electrode 7.Specifically, a data signal supplied to the data line 3 may affect thepixel electrode 7 adjacent to the data line 3, which causes a distortionof the electric field. Particularly, if the pixel electrode 7 is formedparallel to the data line 3 as shown in FIG. 1A, the data line 3 causesstrong signal interference with the pixel electrode 7. To shield thesignal interference from the data line 3, a width of the outermostcommon electrode 6 adjacent to the data line 3 is increased.Accordingly, the aperture ratio is reduced.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an in-plane switchingmode liquid crystal display device and a method for fabricating the samethat substantially obviate one or more of the problems due tolimitations and disadvantages of the related art.

An object of the present invention is to provide an in-plane switchingmode liquid crystal display device and a method for fabricating the samethat improve an aperture ratio of the liquid crystal display device.

Another object of the present invention is to provide an in-planeswitching mode liquid crystal display device and a method forfabricating the same capable of improving image quality.

Another object of the present invention is to minimize a signalinterference in an in-plane switching mode liquid crystal display device

Another object of the present invention is to provide a method forfabricating an in-plane switching mode liquid crystal display devicewith a reduction in a signal interference.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, anin-plane switching mode liquid crystal display device includes a firstsubstrate; a gate line disposed in a first direction on the firstsubstrate; a data line disposed in a second direction on the firstsubstrate, the data line crossing the gate line to define a pixelregion; pixel electrodes and common electrodes disposed in the firstdirection in the pixel region, the pixel electrodes and the commonelectrodes generating an in-plane electric field within the pixelregion; first and second common lines disposed parallel to the data lineat right and left sides of the pixel region; a first common electrodeconnection line connecting at least two common electrodes and forming afirst common electrode overlapping region by overlapping the firstcommon line; and a second common electrode connection line connecting atleast two other common electrodes and forming a second common electrodeoverlapping region by overlapping the second common line, wherein thefirst common electrode overlapping region and the second commonelectrode overlapping region have substantially the same area.

In another aspect, an in-plane switching mode liquid crystal displaydevice includes a first substrate; a gate line disposed in a firstdirection on the first substrate; a data line disposed in a seconddirection on the first substrate, the data line crossing the gate lineto define a pixel region, including a first pixel region and a secondpixel region; one or more first pixel electrode and one or more firstcommon electrode inclined with respect to the first direction andgenerating a first in-plane electric field within the first region; oneor more second pixel electrode and one or more second common electrodeinclined with respect to the first direction and generating a secondin-plane electric field within the second region symmetrically to thefirst in-plane electric field with respect to the first direction; firstand second common lines parallel to the data line at left and rightsides of the pixel region, respectively; a first common electrodeconnection line overlapping the first common line of the first regionand connecting at least two first common electrodes; a second commonelectrode connection line overlapping the second common line of thesecond region and connecting at least two second common electrodes; afirst pixel electrode connection line overlapping the second common lineof the first region and connecting at least two first pixel electrodes;and a second pixel electrode connection line overlapping the firstcommon line of the second region and connecting at least two secondpixel electrodes; wherein a first common electrode overlapping region ofthe first common line and the first common electrode connection line anda second common electrode overlapping region of the second common lineand the second common electrode connection line have the same area, anda first pixel electrode overlapping region of the second common line andthe first pixel electrode connection line and a second pixel electrodeoverlapping region of the first common line and the second pixelelectrode connection line have the same area.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1A is a plane view of a pixel region of a related art IPS-LCDdevice;

FIG. 1B is a cross-sectional view taken along line I-I′ of FIG. 1A;

FIG. 2A is a plane view of an exemplary pixel region according to anembodiment of the present invention;

FIG. 2B is a cross-sectional view taken along line II-IF of FIG. 2A;

FIG. 3 is a plane view of an exemplary pixel region according to anotherembodiment of the present invention;

FIG. 4A is an enlarged view of a region between the data line and thefirst common line of FIG. 2A when a rubbing direction is perpendicularto a direction of the data line;

FIG. 4B is an enlarged view of a region between the data line and thefirst common line of FIG. 2A when a rubbing direction is notperpendicular to a direction of the data line;

FIG. 5 is a plane view of an exemplary pixel region according to anotherembodiment of the present invention;

FIG. 6 is a view for explaining compensation for a viewing angle inaccordance with an embodiment of the present invention;

FIGS. 7A to 7D are plan views which illustrate an exemplary process forfabricating the IPS-LCD device in accordance with an embodiment of thepresent invention; and

FIGS. 8A to 8D are cross sectional views which illustrate an exemplaryprocess for fabricating the IPS-LCD device in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

FIG. 2A is a plane view of an exemplary pixel region according to anembodiment of the present invention. FIG. 2B is a cross-sectional viewtaken along line II-Ii′ of FIG. 2A. Referring to FIG. 2A, an IPS-LCDdevice 100 includes one or more gate line 101 arranged on a transparentfirst substrate 110 in a first direction and one or more data line 103arranged in a second direction, and a pixel region (P) is defined acrossing of the one or more gate line 101 and the one or more data line103. A switching device TFT is formed at the crossing of the gate line101 and the data line 103. The switching device TFT can be a thin filmtransistor, which includes a gate electrode 101 a, a semiconductor layer105 formed on the gate electrode 101 a, and source and drain electrodes102 a and 102 b disposed on the semiconductor layer 105 and separatedfrom each other at a predetermined interval.

At least one pair of common and pixel electrodes 106 and 107 are formedwithin the pixel region (P) to generate an in-plane electric field. Thecommon electrode 106 and the pixel electrode 107 are disposed parallelto each other, and are inclined at an inclination angle (θ) with respectto the gate line 101. The inclination angle (θ) of the common electrode106 and the pixel electrode 107 is in a range of 0 <θ<45°.

Although not shown in the drawing, the gate line 101 may also beinclined to be parallel to the common electrode 106 and the pixelelectrode 107. A rubbing direction (indicated as an arrow on thedrawing) is perpendicular to the data line 103. The rubbing directionwill be described in detail later.

First and second common lines 109 a and 109 b are formed parallel to theone or more data line 103 at left and right sides of the pixel region(P). The first common line 109 a and the second common line 109 b areelectrically connected by a connection line 109. The connection line 109functions as a common electrode within the pixel region (P). Theconnection line 109 performs a function of connecting the first commonline 109 a to the second common line 109 b, and may be disposed at anylocation within the pixel region (P).

FIG. 3 is a plane view of an exemplary pixel region according to anotherembodiment of the present invention. Referring to FIG. 3, the connectionline 109 may be formed at a lower portion of the pixel region (P).Because the LCD device shown in FIG. 3 has a similar structure as to theLCD device of FIG. 2A, the same reference numerals are used for same orlike parts and the description thereof will be omitted. In each of theLCD devices of FIG. 2 and FIG. 3, the connection line 109 connecting thefirst common line 109 a with the second common line 109 b is locatedwithin the pixel region (P). The connection line 109 is disposed at anupper portion of the pixel region in FIG. 2A, while the connection line109 is disposed at a lower portion of the pixel region of FIG. 3.

Referring back to FIG. 2A, the first and second common lines 109 a and109 b supply a common signal to the common electrode 106 and effectivelyblock a signal from the data line 103 to prevent the in-plane electricfield from being distorted by interference with the data signal.Specifically, the data signal supplied to the data line 103 may affectthe pixel electrode 107 adjacent to the data line 103, which may causedistortion of the electric field. However, the signal interferencecaused by the data line 103 can be reduced because the pixel electrode107 has an inclination angle with respect to the data line 103.Accordingly, narrower widths of the first and second common lines 109 aand 109 b adjacent to the data line 103, compared to the related art,may be achieved, thus increasing the aperture ratio.

A common electrode 106 placed toward an upper side of the pixel region(P) has one side electrically connected to a first common electrodeconnection line 116 a. The first common electrode connection line 116 aoverlaps the first common line 109 a to form a first common electrodeoverlapping region (V1). Another common electrode 106 placed toward alower side of the pixel region (P) has one side electrically connectedto a second common electrode connection line 116 b. The second commonelectrode connection line 116 b overlaps a second common line 109 b toform a second common electrode overlapping region (V2). The first commonelectrode overlapping region (V1) and the second common electrodeoverlapping region (V2) have the same area. Also, the first commonelectrode connection line 116 a is electrically connected to the firstcommon line 109 a through a first contact hole 119 formed at the firstoverlapping region (V1), and the second common electrode connection line116 b is electrically connected to the second common line 109 b througha second contact hole 119 formed at the second overlapping region (V2).

A pixel electrode 107 placed toward an upper side of the pixel region(P) has one side electrically connected to a first pixel electrodeconnection line 117 a. The first pixel electrode connection line 117 aoverlaps the second common line 109 b to form a first pixel electrodeoverlapping region (P1). Another pixel electrode 107 placed toward alower side of the pixel region (P) has one side electrically connectedto a second pixel electrode connection line 117 b. The second pixelelectrode connection line 117 b overlaps the first common line 109 b toform a second pixel electrode overlapping region (P2). The first pixelelectrode overlapping region (P1) and the second pixel electrodeoverlapping region (P2) have the same area.

The overlapping regions between the common electrode connection line andthe pixel electrode connection line, respectively, with the common linesat the right and left sides of the pixel are identically formed. Thus,the data line equally affects the right and left sides of the pixel.Specifically, if the data line were to differently affect the right andleft sides of the pixel, image quality would be deteriorated by adifference in signal interference between the data line and the rightand left sides. Accordingly, in an embodiment of the present invention,the overlapping regions between the common electrode connection line andthe pixel electrode connection line, respectively, with the common linesat the right and left sides of the pixel region are identically formed,such that the data line equally affects the right and left sides of thepixel region to prevent the image quality degradation.

As shown in FIGS. 2A and 2B, a storage electrode 114 extending from thefirst pixel electrode connection line 117 a has a first portionoverlapping a front gate line 101 to form a storage capacitor (Cst). Asecond portion of the storage electrode 114 does not overlap the gateline 101 and expands into the pixel region (P) to function as a pixelelectrode that generates an in-plane electric field within the pixelregion together with the adjacent connection line 109. The second pixelelectrode connection line 117 b overlaps a pattern 102 b′ extending fromthe drain electrode 102 b of the thin film transistor TFT and iselectrically connected to the drain electrode 102 b through a draincontact hole 129 formed at the overlapping region.

As shown in the FIG. 2B, the data line 103 is formed on a gateinsulation film 108, and the common electrode 106 and the pixelelectrode 107 are formed on a passivation film 111. Particularly, thecommon electrode 106 and the pixel electrode 107 are formed of atransparent conductive material such as ITO (indium tin oxide) or IZO(indium zinc oxide). As the common electrode 106 and the pixel electrode107 are formed of the transparent conductive material, an aperture ratiomay be improved in comparison with the related art. Namely, in therelated art, the common electrode and the pixel electrode are formed ofopaque metal, which results in reduction of an aperture ratio. However,the present invention may improve the aperture ratio because both thecommon electrode 106 and the pixel electrode 107 are made of atransparent conductive material.

Moreover, in embodiment of the present invention, because the commonelectrode 106 and the pixel electrode 107 are formed on the same plane,on the passivation film 111, a stronger electric field than that in therelated art is generated and applied to a liquid crystal layer betweenthe two electrodes. Such a strong electric field enables higherswitching rate for the liquid crystal molecules within the liquidcrystal layer, which facilitates moving image display.

The storage electrode 114 overlaps the gate line 101 with the gateinsulation film 108 and the passivation film 111 therebetween to formingthe storage capacitor (Cst). A black matrix 121 for preventing lightleakage and a color filter 123 are formed on the second substrate 120.First and second alignment films 112 a and 112 b are applied on facingsurfaces of the first and second substrates 110 and 120. The first andsecond alignment films 112 a and 112 b determine an initial alignmentdirection of a liquid crystal, and a liquid crystal layer 113 is formedtherebetween. The alignment direction of the first alignment film 112 ais perpendicular to the data line 103 and is inclined at a predeterminedangle with respect to the directions of the common electrode 106 and thepixel electrode 107, such that light leakage at a region between thedata line 103, and the first and second common lines 109 a and 109 b isprevented. Accordingly, an area occupied by the black matrix 121 may bereduced. This will now be described in more detail with reference to thedrawings.

FIG. 4A is an enlarged view of a region between the data line and thefirst common line of FIG. 2A when a rubbing direction is perpendicularto a direction of the data line. FIG. 4B is an enlarged view of a regionbetween the data line and the first common line of FIG. 2A when arubbing direction is not perpendicular to a direction of the data line.Here, the state of a liquid crystal molecule when a voltage is notapplied is indicated by a dotted line, and the state of the liquidcrystal molecule when driven by an applied a voltage is indicated by asolid line.

First, as shown in FIG. 4A, when the rubbing direction is perpendicularto the data line 103 and no voltage is applied, the liquid crystalmolecule 113 a is arranged in the rubbing direction of the alignmentfilm and displays a black state when the rubbing direction is parallelto a lower polarization plate. When an applied voltage generates anelectric field, the liquid crystal molecule 113 a is driven according tothe intensity of the applied voltage. Here, because a direction of thegenerated electric field between the data line 103 and the first commonline 109 a is the same as the rubbing direction when the voltage hasbeen applied thereto, the liquid crystal molecule is substantiallyarranged parallel to the rubbing direction. Accordingly, in spite of theapplied voltage, a screen displays black.

In contrast, as shown in FIG. 4B, when the rubbing direction is notperpendicular to the data line 103 and no voltage is applied, the liquidcrystal molecule 113 a is arranged along the rubbing direction anddisplays a black image. However, when a voltage is applied to the dataline 103 and the first common line 109 a, an electric field is generatedbetween the data line 103 and the first common line 109 a in a directionperpendicular to the data line 103. Thus, the liquid crystal molecule isdriven along the direction of the electric field and transmits light.Furthermore, if the rubbing direction and the direction of the electricfield form a 45° angle and the liquid crystal molecule is drivenparallel to the direction of the electric field, a maximum transmittancemay be obtained.

As shown in FIG. 4B, when the rubbing direction does not coincide withthe direction of an electric field between the data line 103 and thefirst common line 109 a, light leakage occurs at a region between thedata line 103 and the first common line 109 a. In order to prevent thelight leakage, a black matrix 121 should be formed on the secondsubstrate 120. When the black matrix 121 is formed on the secondsubstrate 120, an alignment margin should be considered. Therefore, theblack matrix 121 is formed wider than the actual light leakage region,thus decreasing the aperture ratio.

In contrast, as shown in FIG. 4A, because the rubbing direction is setto coincide with the direction of the electric field between the dataline 103 and the first common line 109 a, light leakage does not occurat the region between the data line 103 and the first common line 109 a.Accordingly, the black matrix formed on the second substrate may have aminimum width without regard to an alignment margin for covering theregion between the data line and the common line, thus increasing theaperture ratio.

In an embodiment of the present invention as illustrated in FIGS. 2A, 2Bor FIGS. 3A, 3B, one portion of another side of the common electrode 106which does not contact the first and second common electrode connectionlines 116 a and 116 b, and one portion of another side of the pixelelectrode 107 which does not contact the first and second pixelelectrode connection lines 117 a and 117 b may be bent at apredetermined angle (shown in FIG. 2A). Also, as shown in FIG. 3, aportion (B′) facing a bent portion (B) of the common electrode 106 orthe pixel electrode 107 may also be inclined.

As shown in FIG. 2A, if one side of each of the common electrode 106 andthe pixel electrode 107 is simply bent, the first and second commonlines 109 a and 109 b are formed to be wider than the common electrodeconnection lines 116 a and 116 b and the pixel electrode connectionlines 117 a and 117 b. Also, widths of the first and second common lines109 a and 109 b may be 8 μm or smaller. In contrast, as shown in FIG. 3,if an inclined surface (B′) is formed at a surface facing a bent portion(B), the first and second common lines 109 a and 109 b are formed to benarrower than the common electrode connection lines 116 a and 116 b andthe pixel electrode connection lines 117 a and 117 b.

By bending one portion of the electrodes or inclining a portion (B′)facing a bent portion (B), electric field distortion occurring at anouter edge of the pixel region, namely, at both sides of a commonelectrode 106 and a pixel electrode 107 is minimized in an in-planeelectric field forming region between the two electrodes 106 and 107.Specifically, an electric field formed at both sides of the commonelectrode 106 and the pixel electrode 107 may be distorted because thesetwo electrodes are not disposed as parallel to each other as they are inthe center portion of the pixel. Such a distortion in the electric fieldcan cause an abnormal arrangement of the liquid crystal molecules. Thus,to place the two electrodes generating an in-plane electric field inthis region as parallel as possible, one portion of the pixel electrode107 or the common electrode 109 is bent or an inclined surface (B′) isformed at a region forming an electric field, corresponding to a bentportion (B).

FIG. 5 is a plane view of an exemplary pixel region according to anotherembodiment of the present invention. In accordance with this embodimentof the present invention, a two-domain structure is formed. In thetwo-domain structure, a direction in which a liquid crystal is driven issymmetrical, such that a color shift phenomenon may be minimized byoffsetting abnormal light due to a birefringence characteristic of theliquid crystal. Also, the structure of FIG. 5 is substantially similarto FIGS. 2A and 3, except for symmetrical disposition of a commonelectrode and a pixel electrode at upper and lower sides of the pixelregion.

As shown in FIG. 5, an IPS-LCD device 200 includes a gate line 201arranged on a transparent first substrate 210 in a first direction and adata line 203 arranged in a second direction. A crossing of the gateline 201 and the data line 203 defines a pixel region (P). First andsecond common lines 209 a and 209 b are disposed parallel to the dataline 203 at an outer edge of the pixel region (P). An x-axisperpendicular to the data line 203 and passing through a center of thepixel region defines first pixel region ({circle around (1)}) above thex-axis and a second pixel region ({circle around (2)}) below the x-axis.

At least one pair of a first common electrode 206 a and a first pixelelectrode 207 a generating an in-plane electric field are formed infirst pixel region ({circle around (1)}). The first common electrode 206a and the first pixel electrode 207 a are inclined at an inclinationangle (θ) with respect to the gate line 201. The inclination angle (θ)is within a range of 0<θ<45°. The gate line 201 may be inclined to beparallel to the first common electrode 206 a and the first pixelelectrode 207 a. Also, a first common line 209 a electrically connectedto one side of the first common electrode 206 a and forming a firstcommon electrode overlapping region (V1) together with the first commonline 209 a is formed on the first common electrode 206 a of the firstpixel region ({circle around (1)}). A first pixel electrode connectionline 217 a electrically connected to one side of the first pixelelectrode 207 a and forming a first pixel electrode overlapping region(P1) together with the first common line 209 a are formed on the secondcommon electrode 206 b. Also, widths of the first and second commonlines 209 a, 209 b may be 8 μm or smaller.

At least one pair of a second common electrode 206 b and a second pixelelectrode 207 b generating an in-plane electric field are formed at thesecond pixel region ({circle around (2)}). The second common electrode206 b and the second pixel electrode 207 b are symmetrical to the firstcommon electrode 206 a and the first pixel electrode 207 a disposed atthe first pixel region ({circle around (1)}) on the basis of the x-axis.Namely, the second common electrode 206 b and the second pixel electrode207 b are inclined at an inclination angle (θ) with respect to thex-axis, and the inclination angle (θ) is the same as that of the firstcommon electrode 206 a and the first pixel electrode 207 a.

Also, a second common electrode connection line 216 b electricallyconnected to one side of the second common electrode 206 b and forming asecond common electrode overlapping region (V2) together with the firstcommon line 209 a are formed on the first common electrode 206 a of thesecond pixel region ({circle around (2)}). A second pixel electrodeconnection line 217 b electrically connected to one side of the secondpixel electrode 207 b and forming a second pixel electrode overlappingregion (P2) together with the first common line 209 a is formed on thesecond common electrode 206 b. The first common electrode overlappingregion (V1) of the first pixel region ({circle around (1)}) and thesecond common electrode overlapping region (V2) of the second pixelregion ({circle around (2)}) have the same area, and the first pixelelectrode overlapping region (P1) of the first pixel region ({circlearound (1)}) and the second pixel electrode overlapping region (P2) ofthe second pixel region ({circle around (2)}) have the same area.

By bending portions of the common electrodes 206 a and 206 b and thepixel electrodes 207 a and 207 b, the image quality may be improved. Aninclined surface (B′) may be made at a surface facing a bent portion (B)of the electrode. Here, when the inclined surface (B′) is formed at thesurface facing the bent portion (B), the common lines 209 a and 209 bshould be wider than the common electrode connection lines 216 a and 216b and the pixel electrode connection lines 217 a and 217 b.

As described above, in an embodiment of the present invention, thedisposition of the first common electrode 206 a and the first pixelelectrode 207 a formed at the first pixel region ({circle around (1)})is symmetrical to that of the second common electrode 206 b and thesecond pixel electrode 207 b formed at the second pixel region ({circlearound (2)}) to form a two-domain structure. Accordingly, liquid crystalmolecules of the first pixel region ({circle around (1)}) and the secondpixel region ({circle around (2)}) are arranged symmetrically.

A first storage electrode 214 extending from the first pixel electrodeconnection line 217 a forms a first storage capacitor (Cst1) byoverlapping a front gate line 201. An extending pattern 215 protrudinginto the pixel region from the first common line 209 a forms a secondstorage capacitor (Cst2) at a boundary surface between the first pixelregion ({circle around (1)}) and the second pixel region ({circle around(2)}) together with a second storage electrode 214′ protruding from thepixel electrode connection line and overlapping the extending pattern215. Accordingly, compared to the previous embodiments in FIGS. 2A and3, the second storage capacitor (Cst2) is increased.

The storage capacitor Cst2 charges a gate voltage while a gate signal isapplied to the gate electrode. Then, the charged voltage is maintainedwhile a data voltage is applied to the pixel electrode when the nextgate line is driven, thereby preventing a voltage fluctuation of thepixel electrode. Thus, if the storage capacitor Cst2 is increased,flicker due to the voltage fluctuation of the pixel electrode may beeffectively prevented.

FIG. 6 is a view for explaining compensation for a viewing angle inaccordance with an embodiment of the present invention. As shown in FIG.6, with the two-domain structure in which liquid crystal molecules arearranged symmetrically, a birefringence value of a1 of a first liquidcrystal molecule 213 a is compensated by a birefringence value of a2 ofa second liquid crystal molecule 213 b arranged in a direction oppositeto that of the first liquid crystal molecule 213 a, so that thebirefringence value becomes about zero. Also, a birefringence value ofc1 is compensated by c2. Accordingly, the color shift phenomenon due tothe birefringence characteristic of the liquid crystal is minimized,thereby preventing deterioration of the image quality according to aviewing angle.

As described above, in the IPS-LCD device in accordance with anembodiment of the present invention, a common electrode and a pixelelectrode are formed of a transparent material, an area occupied by ablack matrix may be minimized, and widths of the first and second commonlines disposed at an outer edge of the pixel may be minimized, thusimproving the aperture ratio. Furthermore, right and left regions wherethe common electrode connection line and the pixel electrode connectionline overlap the common lines disposed at both sides of the pixel regionare formed identically, such that the data line equally affects rightand left sides of the pixel and accordingly, the image quality isimproved. Because of the equal influence of the data line on the rightand left sides of the pixel, image deterioration can also be prevented.Furthermore, in an embodiment of the present invention, a two-domainstructure is provided in which a common electrode and a pixel electrodewithin one pixel are symmetrical with respect to an x-axis, therebyimproving a viewing angle characteristic. Although not shown in thedrawing, two pixels may formed a two-domain structure.

FIGS. 7A to 7D are plan views which illustrate an exemplary process forfabricating the IPS-LCD device in accordance with an embodiment of thepresent invention; and FIGS. 8A to 8D are cross sectional views whichillustrate an exemplary process for fabricating the IPS-LCD device inaccordance with an embodiment of the present invention. First, as shownin FIGS. 7A and 8A, a transparent first substrate 310 is provided, thena first metal material, such as Cu, Ti, Cr, Al, Mo, Ta or Al alloy, isdeposited thereon and is patterned to form a gate line 301, a gateelectrode 301 a, first and second common lines 309 a and 309 b disposedperpendicular to the gate line 301, and a connection line 309electrically connecting the first common line 309 a with the secondcommon line 309 b. Then, SiNx, SiOx, or the like is deposited on anentire surface of the substrate including the gate line 301 and thecommon lines 309 a, 309 b by a plasma CVD method to form a gateinsulation film 308.

As shown in FIGS. 7B and 8B, an amorphous silicon and n+ amorphoussilicon is stacked on the gate insulation film 308, and then a secondmetal material such as Cu, Mo.Ta, Al, Cr, Ti, or Al alloy is depositedthereon and is patterned to form a semiconductor layer 305 on the gateelectrode 301 a, a data line 303 disposed perpendicular to the gate line301 and defining a pixel region together with the gate line 301, andsource/drain electrodes 302 a/302 b separated at a predeterminedinterval on the semiconductor layer 305 to form a thin film transistorTFT. An extending pattern 302 b′ of the drain electrode 302 b is alsoformed. Then, an inorganic substance, such as SiNx, SiOx, or the like,or an organic substance, such as benzocyclobutene, acryl, or the like,is applied on the substrate 310, including the thin film transistor TFT,to form a passivation film 311.

Then, as shown in FIGS. 7C and 8C, a first contact hole 319 exposing thefirst and second common lines 309 a and 309 b, and a second contact hole329 exposing the extending pattern 302 b′ of the drain electrode 302 bare formed at selected portions of the passivation film 311 and the gateinsulation film 308.

Then, as shown in FIGS. 7D and 8D, a transparent conductive material,such as ITO (indium tin oxide) or IZO (indium zinc oxide) is depositedon the passivation film 311 including the first and second contact holes319 and 329, and is patterned to form common electrodes 306 and pixelelectrodes 307 inclined with respect to the gate line 201 and forgenerating an in-plane electric field within the pixel region. Here, afirst common electrode connection line 316 a and a second commonelectrode connection line 316 b are also formed. The first commonelectrode connection line 316 a is electrically connected to one side ofa common electrode 306 in an upper part of the pixel region. The firstcommon electrode connection line 316 a overlaps a first common line 309a to form a first common electrode overlapping region (V1). The secondcommon electrode connection line 316 b is electrically connected to oneside of another common electrode 306 in a lower part of the pixelregion. The second common electrode connection line 316 b overlaps asecond common line 309 b to form a second common electrode overlappingregion (V2).

A first pixel electrode connection line 317 a and a second pixelelectrode connection line 317 b are also formed. The first pixelelectrode connection line 317 a is electrically connected to one side ofa pixel electrode 307 at an upper part of the pixel region. The firstpixel electrode connection line 317 a overlaps the first common line 309a to form a first pixel electrode overlapping region (P1). The secondpixel electrode connection line 317 b is electrically connected to oneside of another pixel electrode 307 at a lower part of the pixel region.The second pixel electrode connection line 317 b overlaps the secondcommon line 309 b to form a second pixel electrode overlapping region(P2).

A storage electrode 314 extending from the first pixel electrodeconnection line 317 a and forming a storage capacitor (Cst) byoverlapping a front gate line 301 is also formed. Portions of the pixelelectrode 307 and the common electrode 306 may have a bent structure,and although not shown in the drawing, an inclined surface may be formedat a region facing a bent portion (B). Then, a first alignment film 312a is formed on the first substrate 310. Then, an IPS-LCD device isfabricated by attaching the first substrate 310 to a second substrate320, on which a black matrix 321, a color filter 323, and a secondalignment film 312 b are formed.

As described above, in an embodiment of the present invention, anIPS-LCD device has a high aperture ratio. Particularly, the apertureratiois improved by forming a common electrode and a pixel electrode ofa transparent conductive material. Also, The width of a common line thatis adjacent to a data line is reduced. Signal interference by the dataline is prevented because a common electrode and a pixel electrodegenerating an in-plane electric field are formed in a horizontaldirection and are inclined with respect to a gate line. In addition, thewidth of a black matrix for covering a region between a data line and acommon line adjacent to the data line may be minimized because a rubbingdirection is perpendicular to the data line and thus, light leakage isprevented at the region. Also, image quality is improved by minimizingelectric field distortion because one portion of a common electrode or apixel electrode is bent or a portion facing a bent portion of theelectrode is inclined.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the in-plane switching modeliquid crystal display device and the method for fabricating the same ofthe present invention without departing from the spirit or scope of theinvention. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

1-21. (canceled)
 22. An in-plane switching mode liquid crystal displaydevice comprising: a first substrate; a gate line disposed in a firstdirection on the first substrate; a data line disposed in a seconddirection on the first substrate, the data line crossing the gate lineto define a pixel region, including a first pixel region and a secondpixel region; one or more first pixel electrode and one or more firstcommon electrode inclined with respect to the first direction andgenerating a first in-plane electric field within the first region; oneor more second pixel electrode and one or more second common electrodeinclined with respect to the first direction and generating a secondin-plane electric field within the second region symmetrically to thefirst in-plane electric field with respect to the first direction; firstand second common lines parallel to the data line at left and rightsides of the pixel region, respectively; a first common electrodeconnection line overlapping the first common line of the first regionand connecting at least two first common electrodes; a second commonelectrode connection line overlapping the second common line of thesecond region and connecting at least two second common electrodes; afirst pixel electrode connection line overlapping the second common lineof the first region and connecting at least two first pixel electrodes;and a second pixel electrode connection line overlapping the firstcommon line of the second region and connecting at least two secondpixel electrodes; wherein a first common electrode overlapping region ofthe first common line and the first common electrode connection line anda second common electrode overlapping region of the second common lineand the second common electrode connection line have the same area, anda first pixel electrode overlapping region of the second common line andthe first pixel electrode connection line and a second pixel electrodeoverlapping region of the first common line and the second pixelelectrode connection line have the same area.
 23. The device of claim22, wherein one side of at least one of the first common electrode andthe first pixel electrode is bent.
 24. The device of claim 22, whereinone side of at least one of the second common electrode and the secondpixel electrode is bent.
 25. The device of claim 24, wherein the firstand second common lines are wider than the first and second commonelectrode connection lines and the first and second pixel electrodeconnection lines.
 26. The device of claim 25, wherein a region facingthe bent side is inclined.
 27. The device of claim 22, wherein the firstand second common lines are wider than the first and second commonelectrode connection lines and the first and second pixel electrodeconnection lines.
 28. The device of claim 22, wherein the first andsecond common electrodes and the first and second pixel electrodes areformed of a transparent conductive material.
 29. The device of claim 28,wherein the transparent conductive material is one of indium tin oxide(ITO) and IZO (indium zinc oxide).
 30. The device of claim 22, wherein acontact hole electrically connects the first and second common lineswith the first and second common electrode connection lines.
 31. Thedevice of claim 22, wherein a rubbing direction of the first substrateis parallel to the first direction.
 32. The device of claim 22, furthercomprising a connection line electrically connecting the first commonline with the second common line.
 33. The device of claim 32, whereinthe connection line is placed at the first region.
 34. The device ofclaim 32, wherein the connection line is placed at the second region.35. The device of claim 22, further comprising a storage electrodeextending from the first pixel electrode connection line and forming astorage capacitor by overlapping a front gate line.
 36. The device ofclaim 22, wherein the first and second common lines are 8 μm or smaller.37. The device of claim 22, further comprising a second substrate and aliquid crystal layer formed between the first substrate and the secondsubstrate, wherein the second substrate comprises a black matrix and acolor filter, and the black matrix has a minimum width regardless of analignment margin for covering a region between the data line and thecommon line.
 38. An in-plane switching mode liquid crystal displaydevice comprising: a first substrate; a gate line disposed in a firstdirection on the first substrate; a data line disposed in a seconddirection on the first substrate, the data line crossing the gate lineto define a pixel region; pixel electrodes and common electrodesdisposed in the first direction in the pixel region, the pixelelectrodes and the common electrodes generating an in-plane electricfield within the pixel region; a first common line disposed parallel tothe data line at left side of the pixel region; a second common linedisposed parallel to the data line at right side of the pixel region; afirst common electrode connection line connecting at least two commonelectrodes and forming a first common electrode overlapping region byoverlapping the first common line; a second common electrode connectionline connecting at least two other common electrodes and forming asecond common electrode overlapping region by overlapping the secondcommon line; a first pixel electrode connection line connecting at leasttwo pixel electrodes and forming a first pixel electrode overlappingregion by overlapping the first common line; and a second pixelelectrode connection line connecting at least two other pixel electrodesand forming a second pixel electrode overlapping region by overlappingthe second common line, wherein the first common electrode overlappingregion and the second common electrode overlapping region havesubstantially the same area, and the first pixel electrode overlappingregion and the second pixel electrode overlapping region havesubstantially the same area, wherein the first common electrodeoverlapping region is formed at the different area from that of thefirst pixel electrode overlapping region, and wherein the second commonelectrode overlapping region is formed at the different area from thatof the second pixel electrode overlapping region, wherein one side of atleast one of the common electrodes and the pixel electrodes is bent, anda region facing the bent side is inclined, wherein the first and secondcommon lines are narrower than the common electrode connection line andthe pixel electrode connection line.
 39. The device of claim 38, whereinthe common electrodes and the pixel electrodes are inclined with respectto of the first direction.
 40. The device of claim 39, wherein thecommons electrode and the pixel electrodes have an inclination of about45° or less with regard to the first direction.
 41. The device of claim38, wherein the common electrodes and the pixel electrodes are formed onthe same plane.
 42. The device of claim 38, wherein a contact holeelectrically connecting the first common line with the first commonelectrode connection line and electrically connecting the second commonline with the second common electrode connection line is formed.
 43. Thedevice of claim 38, further comprising a second substrate and a liquidcrystal layer formed between the first substrate and the secondsubstrate, wherein the second substrate comprises a black matrix and acolor filter, wherein a rubbing direction of the first substrate isparallel to the first direction and thereby the black matrix has aminimum width regardless of an alignment margin for covering a regionbetween the data line and the common line.
 44. The device of claim 38,further comprising a connection line electrically connecting the firstand second common lines.
 45. The device of claim 44, wherein theconnection line is placed at an upper portion of the pixel region. 46.The device of claim 44, wherein the connection line is placed at a lowerportion of the pixel region.
 47. The device of claim 38, furthercomprising a storage electrode extending from the pixel electrodeconnection line and forming a storage capacitor by overlapping a frontgate line.
 48. The device of claim 38, wherein widths of the first andsecond common lines are 8 μm or smaller.